#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int main()
{
	int i=0;
	float t = 1.0;
	float sum = 0.0;
	for (i = 1;i <= 100;i++)
	{
		sum=sum+t/i;
		t = -t;
	}
	printf("%lf\n", sum);
	return 0;
}